Back rest cushion



FIG. 1 is a front and right side perspective view of a back rest cushion showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side elevational view thereof, the left side being a mirror image of that shown;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a top plan view thereof; and

FIG. 6 is a bottom plan view thereof.

The cross-hatching employed throughout the views is understood to represent a conventional fabric material. 

The ornamental design for a back rest cushion, as shown and described. 